1 //===-- sanitizer_stacktrace.cc -------------------------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file is shared between AddressSanitizer and ThreadSanitizer 11 // run-time libraries. 12 //===----------------------------------------------------------------------===// 13 14 #include "sanitizer_common.h" 15 #include "sanitizer_flags.h" 16 #include "sanitizer_stacktrace.h" 17 18 namespace __sanitizer { 19 20 uptr StackTrace::GetPreviousInstructionPc(uptr pc) { 21 #if defined(__arm__) 22 // Cancel Thumb bit. 23 pc = pc & (~1); 24 #endif 25 #if defined(__powerpc__) || defined(__powerpc64__) 26 // PCs are always 4 byte aligned. 27 return pc - 4; 28 #elif defined(__sparc__) 29 return pc - 8; 30 #else 31 return pc - 1; 32 #endif 33 } 34 35 uptr StackTrace::GetCurrentPc() { 36 return GET_CALLER_PC(); 37 } 38 39 void StackTrace::FastUnwindStack(uptr pc, uptr bp, 40 uptr stack_top, uptr stack_bottom, 41 uptr max_depth) { 42 CHECK_GE(max_depth, 2); 43 trace[0] = pc; 44 size = 1; 45 uhwptr *frame = (uhwptr *)bp; 46 uhwptr *prev_frame = frame - 1; 47 if (stack_top < 4096) return; // Sanity check for stack top. 48 // Avoid infinite loop when frame == frame[0] by using frame > prev_frame. 49 while (frame > prev_frame && 50 frame < (uhwptr *)stack_top - 2 && 51 frame > (uhwptr *)stack_bottom && 52 IsAligned((uptr)frame, sizeof(*frame)) && 53 size < max_depth) { 54 uhwptr pc1 = frame[1]; 55 if (pc1 != pc) { 56 trace[size++] = (uptr) pc1; 57 } 58 prev_frame = frame; 59 frame = (uhwptr *)frame[0]; 60 } 61 } 62 63 static bool MatchPc(uptr cur_pc, uptr trace_pc, uptr threshold) { 64 return cur_pc - trace_pc <= threshold || trace_pc - cur_pc <= threshold; 65 } 66 67 void StackTrace::PopStackFrames(uptr count) { 68 CHECK_LT(count, size); 69 size -= count; 70 for (uptr i = 0; i < size; ++i) { 71 trace[i] = trace[i + count]; 72 } 73 } 74 75 uptr StackTrace::LocatePcInTrace(uptr pc) { 76 // Use threshold to find PC in stack trace, as PC we want to unwind from may 77 // slightly differ from return address in the actual unwinded stack trace. 78 const int kPcThreshold = 288; 79 for (uptr i = 0; i < size; ++i) { 80 if (MatchPc(pc, trace[i], kPcThreshold)) 81 return i; 82 } 83 return 0; 84 } 85 86 } // namespace __sanitizer 87
